LSI 53C875A - Manual (Page 81)

PCI Bus Interface Signals 3-5
3.3.2 Address and Data Signals
Table 3.3 describes Address and Data signals.
Table 3.3 Address and Data Signals
Name PQFP BGA Type Strength Description
AD[31:0] 150, 151,
153, 154,
156, 157,
159, 160, 3,
5, 6, 7, 9,
11–13, 28–
30, 32, 34–
36, 38, 40,
41, 43, 44,
46, 47, 49,
50 B5, C5, A4,
B4, A3, C4,
D4, A2, C2,
E5, C1, D3,
E4-E1, H5,
J1, J2, H6,
K2, J4, L1,
L2, M1, N1,
M3, L3, N3,
L4, K5, N4 T/S 8 mA
PCI
Physical Dword Address and Data are
multiplexed on the same PCI pins. A bus
transaction consists of an address phase
followed by one or more data phases.
During the first clock of a transaction,
AD[31:0] contain a 32-bit physical byte
address. If the command is a DAC,
implying a 64-bit address, a second
address phase is required. During the
first phase, AD[31:0] will contain the
lower 32 bits of the address followed by
a second phase with AD[31:0] containing
the upper 32 bits of the address. During
subsequent clocks, AD[31:0] contain
data. PCI supports both read and write
bursts. AD[7:0] define the least
significant byte, and AD[31:24] define the
most significant byte.
C_BE[3:0] 1, 15, 26,
39 A1, F3, H3,
K4 T/S 8 mA
PCI
Bus Command and Byte Enables are
multiplexed on the same PCI pins.
During the address phase of a
transaction, C_BE[3:0]/ define the bus
command. During the data phase,
C_BE[3:0]/ are used as byte enables.
The byte enables determine which byte
lanes carry meaningful data. C_BE[0]/
applies to byte 0, and C_BE[3]/ to byte 3.
PAR 25 H1 T/S 8 mA
PCI
Parity is the even parity bit that protects
the AD[31:0] and C_BE[3:0]/ lines.
During the address phase, both the
address and command bits are covered.
During data phase, both data and byte
enables are covered.